In Celtics nation, the buzz about Al Horford is still at full force. As of now, most have written about how he can fit in and help our team. What most have been missing is how exactly the Celtics can help him. For all the great things that Al Horford can do, rebounding has been a real weak point. In the last three years his total rebounding percentage has dropped from 14.8 to 13.4 to 12.4 percent last season. Traditionally, Al Horford has never been a strong rebounder, at best posting an 18% total rebounding percentage his rookie season. However, the past two years have been a bit troubling with his defensive rebounding percentage dropping below 20%. Some have pointed to that as a direct correlation to his aging, but I think it's a product of the Hawks system.
While the majority of the league tends to "ICE" the pick and roll (PnR), the Hawks are one of the few teams that prefers to hedge as shown above. This style worked for them last year, as they were the second-best defense, and teams struggled against this strategy for the most part. However, the downside of hedging the way the Hawks do is that it puts an enormous amount of pressure on the bigs. Not only do they have to chase out point guards and then run back to grab their man but they're also more susceptible to being switched onto a guard, putting their point guard in a mismatch down low and keeping them from rebounding. Guards also have a tendency to just "give off" the pick and roll handler to the big instead of fighting over screens—which compounds the issue.
In Boston, the Celtics usually attack the PnR by ICE'ing.
As you can see, Sullinger drops back and contains while Crowder fights over the pick and gets back to his man. Because Sullinger didn't have to over-commit, he's able to re-establish good defensive positioning back onto his man without having to exert immense energy running to track him down. Though the the Hawks had a couple of good perimeter defenders in Kent Bazemore and Thabo Sefolosha, they simply don't compare to the girth of defensive studs the Celtics have in Avery Bradley, Marcus Smart, Jae Crowder, Terry Rozier, and Jonas Jerebko. All of those guys can move quickly laterally and can fight over screens. This strategy will lead to better opportunities for Al Horford to be in good rebounding positions where he can be grab defensive boards and do more stuff like this:
The Celtics will still need to find another player who can rebound in general, but the troubles with Horford may not be as serious as his numbers show. One name that I could see making a return to Boston is none other than Kris Humphries. His numbers are comparable to Jared Sullinger, if you're only looking for a big who can rebound, defend in space, and run the floor. Look out for his name if Sullinger gets priced out.